The present invention realtes to a novel monitoring system for monitoring the performance or function of a plurality of parts or stations in various machines and providing an alarm in the event of a failure or significant deviation in the operation of the machine.
While monitoring systems incorporating features of the present invention may be adapted for use in association with many different machines or processes, the invention is particularly suitable for incorporation in monitoring systems heretofore proposed for use in agriculture machines such as planters and combines. By way of example only, reference is made to U.S. Pat. No. 3,723,989, which shows a planter monitoring system capable of individually sensing the passage of seed through a plurality of seed planting chutes in a conventional multiple row planter and of providing both a visual light signal and an audible signal in the event there is an interruption in the flow of the seeds through any one of the seed delivery chutes. As a further example, reference is made to U.S. Pat. No. 3,739,367, which discloses a monitoring system adaptable for monitoring the rotational speed of a plurality of shafts in a machine such as a combine and of providing both a visual light and audible alarm signal in the event one of the shafts stops or slows below a predetermined speed.
It has been found that during the normal operation of machines such as combines or planters, there are times when an operator desires to slow or discontinue temporarily a machine function being monitored without switching off the monitoring system. For example, during combine operations, when the grain tank of the combine becomes full, the operator needs to unload the grain. In order to accomplish the unloading operation, the operator manipulates the machine controls so that the monitored shafts are stopped while an auger or the like is activated for discharging the grain from the tank. With monitoring systems heretofore in use, the stopping of the monitored shafts causes the audible alarm signal to sound in the absence of the provision of some mechanical disconnect switch. The sound of the audible signal during the entire unloading procedure may be quite disturbing to the operator.
With heretofore proposed planter monitoring systems, when an operator slows down at the end of a row to turn the tractor and planter around for planting another row, the audible signal comes on and sounds during the slow-down and turn-around. Again, the audible alarm signals during this period can be quite distracting and disturbing to an operator.